Controllable electronic switch

ABSTRACT

A controllable electronic switch for, e.g., controlling power distribution comprises a deformable member such as a bimetal arm that can be deformed to break an electrical path. The deformable member may be anchored at one end and in controllable contact with an electrical conductor at the other end. A heating element, such as a coil, can be used to selectively heat the deformable member. The controllable electronic switch can alternatively comprise a deformable member that is terminated in a wedge-shaped member. When the deformable member bends in response to being heated, the wedge-shaped member forces apart a pair of contacts thus breaking an electrical path. The wedge-shaped member and/or associated structures may be configured as a cam mechanism with multiple latching positions.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application of U.S. application Ser.No. 14/660,582, filed Mar. 17, 2015, entitled “Controllable ElectronicSwitch”, which is a continuation of U.S. application Ser. No.13/103,023, filed May 6, 2011, which is a continuation of U.S.application Ser. No. 12/569,349 filed Sep. 9, 2009, entitled“Controllable Electronic Switch”, now U.S. Pat. No. 7,961,073, which isa continuation of U.S. application Ser. No. 11/849,064, filed Aug. 31,2007, entitled “Controllable Electronic Switch”, now U.S. Pat. No.7,688,175, which is a continuation of Ser. No. 10/900,971 filed Jul. 28,2004, entitled “Controllable Electronic Switch,” now U.S. Pat. No.7,265,652 which is a continuation-in-part of U.S. application Ser. No.10/307,222 filed Nov. 27, 2002, entitled “Controllable Electronic SwitchWith Interposable Non-Conductive Element to Break Circuit Path,” nowU.S. Pat. No. 6,825,750, which is a continuation-in-part of U.S.application Ser. No. 09/903,403 filed Jul. 10, 2001, entitled“Controllable Electronic Switch,” now U.S. Pat. No. 6,636,141, all ofwhich are hereby incorporated by reference as if set forth fully herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention generally pertains to electronic switchesand, more specifically, to controllable electronic switches forcontrolling power distribution.

2. Background

Power switches have been used for many years to connect and disconnectpower sources to loads. A common type of power switch is a circuitbreaker, which generally provides a function of preventing an excessiveamount of current from being drawn from the power source or into theload, by breaking the electrical circuit path between the source andload when the current limit is reached. A typical circuit breaker has abimetal arm through which travels a power signal from the source to theload. One end of the bimetal arm is connected to the power signal line,while the other end of the bimetal arm is connected to an electricalconductor from which the power can be distributed to the load. When toomuch current travels through the bimetal arm, the heat from the currentcauses the bimetal arm to deform or bend in a predictable manner, whichcauses the bimetal arm to break contact with the electrical conductor,resulting in a break between the power signal and the load. In thismanner, the source and load are both protected from currents whichexceed a certain limit.

While circuit breakers are useful for protecting against high currentlevels, they are generally passive circuit elements whose responsedepends entirely upon the amount of power being drawn by the load. Theytypically do not provide active control of a power signal line. However,some resettable circuit breakers have been proposed, which utilize, forexample, a spring-operated mechanism allowing a remote operator to openand close the contacts of the circuit breaker. An example of such acircuit breaker is disclosed in U.S. Pat. No. 3,883,781 issued to J.Cotton.

Other types of remotely controlled or operated circuit breakers aredescribed, for example, in U.S. Pat. No. 5,381,121 to Peter et al., andU.S. Pat. No. 4,625,190 to Wafer et al. These circuit breakers involverather elaborate mechanisms that, due to their complexity, would beexpensive to manufacture and potentially subject to mechanical wear orfailure.

Besides circuit breakers, other types of circuits have been utilized incontrolling power signals. However, these other types of circuits havedrawbacks as well. For example, solid state switches (e.g., transistorsor silicon-controlled rectifiers (SCRs)) can be used as switches betweena power source and load, for controlling distribution of the powersignal to the load. However, transistors and SCRs generally have limitedpower ratings and, at high current levels, can become damaged orshorted. Moreover, transistors or SCRs with high power ratings can berelatively expensive.

It would therefore be advantageous to provide a controllable electronicswitch capable of selectively connecting or disconnecting a power sourceto a load. It would further be advantageous to provide such a switchthat is reliable, durable, and low-cost, and that can handle relativelyhigh power demands, such as may be required for residential orcommercial applications.

SUMMARY OF THE INVENTION

The invention in one aspect is generally directed to a controllableelectronic switch for controlling power distribution.

In one embodiment, a controllable electronic switch comprises adeformable member (e.g., a bimetal member or arm) anchored at one endand in controllable contact with an electrical conductor at the otherend. An incoming power wire is connected to the deformable member nearthe contact point with the electrical conductor. A heating element (suchas a coil) is coupled to the deformable member, and is controlled by aswitch control signal. When the switch control signal is not asserted,the heating element is inactive, and power is delivered through theincoming power wire across the end of the deformable member to theelectrical conductor, from which it can be further distributed to theload. When the switch control signal is asserted, the heating elementheats up causing the deformable member to bend until the contact withthe electrical conductor is broken. The electrical path from theincoming power wire to the electrical conductor (and hence, to the load)is then broken. So long as the switch control signal is asserted, theheating element continues to keep the deformable member bent and theelectrical path broken.

In various embodiments as disclosed herein, a controllable electronicswitch comprises a deformable member (such as a bimetal arm) that isterminated in a wedge-shaped member. When the deformable member deformsin response to a control signal, the wedge-shaped member forces apart apair of contacts thus breaking an electrical path. The wedge-shapedmember and/or associated structures may be configured as a cam mechanismwith multiple latching positions.

Further embodiments, variations and enhancements are also disclosedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a bimetal-based circuit breaker asknown in the art.

FIG. 2-1 is a diagram illustrating an example of the flow of electricitywhen the circuit breaker of FIG. 1 is closed (normal operation), andFIG. 2-2 is a diagram illustrating an example of how the bimetal of thecircuit breaker breaks the circuit connection when an over-currentsituation occurs.

FIG. 3 is a diagram of a controllable electronic switch in accordancewith one embodiment as disclosed herein.

FIG. 4-1 is a diagram illustrating an example of the flow of electricitywhen the electronic switch of FIG. 3 is closed, and FIG. 4-2 is adiagram illustrating how the bimetal of the electronic switch of FIG. 3breaks the circuit connection in response to assertion of a controlsignal.

FIG. 5 is a block diagram illustrating a conceptual diagram of acontrollable electronic switch in accordance with one or moreembodiments as disclosed herein.

FIG. 6 is a diagram of another embodiment of a controllable electronicswitch using a wedge to break electrical contacts in a circuit path.

FIG. 7 is a diagram showing an example of how the controllableelectronic switch shown in FIG. 6 breaks an electrical connection.

FIG. 8 is a diagram of another embodiment of a controllable electronicswitch using a wedge to break electrical contacts in a circuit path,having a mechanical cam with multiple latching positions.

FIGS. 9-1, 9-2 and 9-3 are diagrams illustrating the controllableelectronic switch of FIG. 8 with the latch in an engaged position withrespect to the cam.

FIGS. 10-1 through 10-8 are diagrams illustrating different latchingpositions of the cam of the controllable electronic switch of FIG. 8.

FIG. 11 is a diagram of yet another embodiment of a controllableelectronic switch using a wedge to break electrical contacts in acircuit path, having a mechanical cam with multiple latching positions.

FIG. 12 is a diagram showing an example of how the controllableelectronic switch shown in FIG. 11 breaks an electrical connection.

FIGS. 13, 14, and 15 are simplified schematic diagrams illustratingexamples of control circuits or portions thereof that may be used withvarious controllable electronic switches disclosed herein.

FIG. 16 is a diagram of one embodiment of a switch control circuit asmay be used in connection with various controllable electronic circuitembodiments shown or described herein.

FIG. 17 is a diagram of another embodiment of a switch control circuitas may be used in connection with various controllable electroniccircuit embodiments as shown or described herein.

FIG. 18 is a diagram of another embodiment of a controllable electronicswitch.

FIGS. 19-1 and 19-2 are diagrams illustrating operation of thecontrollable switch depicted in FIG. 18.

FIG. 20 is a diagram of a controllable electronic switch, utilizing apair of opposing deformable members.

FIGS. 21-1 and 21-2 are diagrams illustrating operation of thecontrollable switch depicted in FIG. 20.

FIG. 22 is a diagram of another embodiment of a controllable electronicswitch having opposing deformable members, along with an overridecontrol.

FIGS. 23-1 and 23-2 are diagrams illustrating operation of thecontrollable switch depicted in FIG. 22.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a conceptual diagram of a bimetal-based circuit breaker 100 asknown in the art. As illustrated in FIG. 1, the circuit breaker 100comprises a bimetal arm 101 which is formed of two metallic layers 102,103. The bimetal arm 101 is anchored at one end 106, and connects atthat end 106 to an incoming power signal line 115. At its other end 107,the bimetal arm 101 resides in electrical contact with an electricalconductor 120. The electrical conductor 120 may be connected to a load(not shown) and, in normal operation (i.e., normal current flow), powerfrom the power signal line 115 is conducted through the bimetal arm 101and the electrical conductor 120 to the load.

The metallic substances of the different metallic layers 102, 103 of thebimetal arm 101 are selected to have different thermal properties suchthat they heat at different rates. In particular, the metallic substanceof the lower metallic layer 102 heats faster than the metallic substanceof the upper metallic layer 103. When the amount of current travelingthrough the bimetal arm 101 is within “normal” limits, the amount ofheating caused by the current passing through the bimetal arm 101 (whichhas a natural resistivity) is small and the bimetal arm 101 does notdeform. However, when the amount of current traveling through thebimetal arm 101 exceeds an over-current limit (which is determinedlargely by the relative thermal properties of the metallic substancesused in the metallic layers 102 and 103), the lower metallic layer 102heats more rapidly than the upper metallic layer 103 and causes thebimetal arm 101 to bend, thus breaking the electrical circuit pathbetween the incoming power signal line 115 and the electrical conductor120.

This operation can be illustrated by the diagrams of FIGS. 2-1 and 2-2.FIG. 2-1 is a diagram illustrating an example of the flow of electricitywhen the circuit breaker 100 of FIG. 1 is closed (normal operation), andFIG. 2-2 is a diagram illustrating an example of how the bimetal arm 101of the circuit breaker 100 breaks the circuit connection when anover-current situation occurs. As shown in FIG. 2-1, a power signaltravels through incoming power wire 115 (marked “IN”) through thebimetal arm 101 and across contacts 112, to the electrical conductor 120(marked “OUT”). So long as the amount of current in the power signal isbelow the over-current limit, the amount of heating caused by thecurrent passing through the bimetal arm 101 is small, and the bimetalarm 101 does not deform. However, as now shown in FIG. 2-2, when theamount of current traveling through the bimetal arm 101 exceeds theover-current limit, the current heats the bimetal arm 101, but the lowermetallic layer 102 heats more rapidly than the upper metallic layer 103thus causing the bimetal arm 101 to bend. As a result, the contacts 112gradually separate, breaking the electrical circuit path between theincoming power signal line 115 and the electrical conductor 120. Theamount of current needed to cause the circuit breaker 100 to “trip”depends upon the relative thermal properties of the two metallic layers102, 103 of the bimetal arm 101.

After being tripped, gradually the bimetal arm 101 of the circuitbreaker 100 will cool, until eventually the bimetal arm 101 is no longerdeformed. As this occurs, the contacts 112 once again form an electricalconnection, allowing the power signal to pass from the incoming powerwire 115 to the electrical conductor 120.

FIG. 3 is a diagram of a controllable electronic switch 300 inaccordance with one embodiment as disclosed herein. As shown in FIG. 3,the controllable electronic switch 300 comprises a deformable member 301which may be formed in the general shape of an arm (similar to thatshown in FIG. 1 or other embodiments shown herein) and may be comprisedof two layers 302, 303 having different thermal properties. Preferably,the two layers 302, 303 are metallic in nature, although any durablesubstance that bends when heated can be used. As further shown in FIG.3, the deformable member 301 is preferably anchored at one end 306 to anon-conductive surface 315. At its other end, the deformable member 301preferably resides in contact with an electrical conductor 320 throughcontacts 312. An incoming power wire 325 is connected to the deformablemember 301 preferably near the contact point with the electricalconductor 320, so as to minimize any power dissipation caused by thecurrent running through the deformable member 301, and also so as toavoid heating the deformable member 301 to any significant degreeregardless of the current being drawn. The electrical conductor 320 maybe connected to a load (not shown) and, in normal operation (that is, inthe absence of assertion of a switch control signal, as explainedbelow), power from the power signal line 325 is conducted through thedeformable member 301 and the electrical conductor 320 to the load.

The metallic substances of the different metallic layers 302, 303 of thedeformable member 301 are preferably selected to have different thermalproperties such that they heat at different rates. In particular, themetallic substance of the lower metallic layer 302 preferably heatsfaster than the metallic substance of the upper metallic layer 303. Whenheat is applied to the deformable member 301, the faster heating of thelower metallic layer 302 as compared to the upper metallic layer 303causes the deformable member 301 to bend, similar to a circuit breaker100, thus breaking the electrical circuit path between the incomingpower signal line 325 and the electrical conductor 320.

As further illustrated now in FIG. 3, a heating element 345 (such as aresistive coil) is coupled (e.g., wrapped around, in the case of aresistive coil) to the deformable member 301. The heating element 345 ispreferably controlled by a switch control circuit 340 connected theretoby a pair of signal lines 341, 342. When the switch control signaloutput from the switch control circuit 340 is not asserted, the heatingelement 345 is effectively disconnected (and thus inactive), and poweris delivered through the incoming power wire 325 across the end 307 ofthe deformable member 301, via contacts 312, to the electrical conductor320, from which it can be further distributed to the load. Thisoperation is illustrated in FIG. 4-1. When, however, the switch controlsignal from the switch control circuit 340 is asserted, the heatingelement 345 heats up due to the effect of the current flowing throughthe heating element 345. Since the lower metallic layer 302 heats morerapidly than the upper metallic layer 303, the deformable member 301starts to bend. Eventually, as a result of this bending, the contacts312 gradually separate, breaking the electrical circuit path between theincoming power signal line 325 and the electrical conductor 320, asillustrated in FIG. 4-2.

So long as the switch control signal from the switch control circuit 340is asserted, the heating element 345 continues to keep the deformablemember 301 bent and the electrical path between the incoming power wire325 and the electrical conductor 320 disconnected. Once the switchcontrol signal from the switch control circuit 340 is de-asserted, thedeformable member 301 gradually cools, until eventually the deformablemember 301 is no longer deformed. As this occurs, the contacts 312 onceagain form an electrical connection, allowing the power signal to passfrom the incoming power wire 325 to the electrical conductor 320 andthen to the load.

In one aspect, the controllable electronic switch 300 illustrated inFIG. 3 can provide a convenient, inexpensive mechanism for controllingthe distribution of power from a source to a load. Moreover, thecontrollable electronic switch 300 need not consume any power when thedeformable member 301 is in a closed position, and only requires minimalpower to cause the deformable member 301 to open.

The incoming power wire 325 may be connected to the deformable member301 in any of a variety of manners. The incoming power wire 325 may, forexample, simply be welded, spliced or soldered to the moving end 307 ofthe deformable member 301. Any form of attaching the incoming power wire325 to the deformable member 301 will suffice so long as electricityconducts between the incoming power wire 325 and the electricalconductor 320 when the deformable member 301 is in a switch-closedposition.

FIG. 5 is a block diagram illustrating a more general embodiment of acontrollable electronic switch 500. As illustrated in FIG. 5, thecontrollable electronic switch 500 comprises a deformable member 501which controllably connects an incoming power wire 525 to an electricalconductor 520. A heating element 545 is coupled to the deformable member501, and is controlled by a switch control circuit 540. The deformablemember 501, which may take the form of, e.g., a bimetal member or arm,preferably allows the incoming power wire 525 to conduct a power signalto the electrical conductor 520 when the deformable member 501 is notbeing heated by the heating element 545, but preferably causes theconnection between the incoming power wire 525 to the electricalconductor 520 to be physically broken when then deformable member 501 isheated by the heating element 545. The heating element 545 may comprise,e.g., a resistive coil or other resistor, and, if a resistive coil, maybe conveniently wound around the deformable member 501 if embodied as abimetal member or arm.

In either of the embodiments illustrated in FIGS. 3 and 5, thedeformable member 301 or 501 need not be uniformly straight and, infact, can be any shape so long as, when heated, it bends in apredictable manner so as to break the electrical connection between theincoming power wire 325 or 525 and the electrical conductor 320 or 520.Moreover, although the deformable member 301 or 501 is described in apreferred embodiment as a bimetal arm having two metallic layers, italternatively could be made out of any other material (metallic orotherwise) that bends in a predictable manner. Because no current needsto travel from one end of the deformable member 301 or 501 to the otherend (unlike a circuit breaker), the deformable member 301 or 501 may, ifdesired, have non-conductive or insulating portions separating thevarious areas of the deformable member 301 or 501 from one another. Forexample, a non-conductive portion (e.g., plastic) could be placedbetween the area of the deformable member 301 or 501 coupled to theheating element 345 or 545 and either end of the deformable member 301or 501 (e.g., either end 306 and/or 307 of the deformable member 301 inthe example of FIG. 3). Further, the end of the deformable member 301through which power is conducted (e.g., end 307 in FIG. 3) need not bebimetal, but could be a uniform conductive material (e.g., a singlemetal). Alternatively, the deformable member 301 or 501 could haveadditional (i.e., more than two) layers. The primary quality of thedeformable member 301 or 501 is that it bends or otherwise deformssufficiently when heated so as to break the electrical connection of thepath of the power signal (e.g., by separating contacts 312 in theexample of FIG. 3).

The switch control signal output from the switch control circuit 340 or540 to the heating element 345 or 545 is preferably a direct current(DC) signal, but could also be an alternating current (AC) signal orhybrid signal. When the switch control signal is not asserted, theswitch control circuit 340 may simply short the heating element 345 or545 (e.g., by shorting wires 341, 342 in the example of FIG. 3), or elsesimply isolate the heating element 345 or 545 through a buffer or otherisolation circuit.

While the heating elements 345 and 545 in FIGS. 3 and 5 have beendescribed in preferred embodiments as a resistive coil, the heatingelement 345 or 545 could take other forms or configurations. Forexample, if embodied as a resistive coil, the heating element 345 or 545need not be wound around the deformable member 301 or 501. The heatingelement 345 or 545 could be a different type of resistor besides aresistive coil. However, a resistive coil is preferred as the heatingelement 345 or 545 because it provides relatively even heating over agiven area, and is relatively simple to implement and is relativelyinexpensive.

The speed of response of the deformable member 301 or 501 to the switchcontrol circuit 340 or 540 may or may not be critical, depending uponthe particular application. If the speed of response is not verycritical, then the switch control signal can be a very low power signal.If faster response time is desired, the switch control signal can beincreased in power, thus causing more rapid heating of the heatingelement 345 or 545. The switch control circuit 340 or 540 may beprovided with its own power source (e.g., a battery), or else it mayobtain power from the incoming power wire 325 or 525 or some otheravailable source. The switch control circuit 340 or 540 may be activatedby a manual switch (not shown) which causes assertion of the switchcontrol signal and, therefore, eventual opening of the controllableelectronic switch 300 or 500, or else may be activated by a remoteelectronic signal.

FIG. 6 is a diagram of another embodiment of a controllable electronicswitch 600 using a wedge to physically break electrical contacts in acircuit path. As illustrated in FIG. 6, the controllable electronicswitch 600 comprises a generally elongate deformable member 601 which isformed of two layers 602, 603, similar in nature to the deformablemember 301 described previously with respect to FIG. 3. In a preferredembodiment, the deformable member 601 comprises a bimetal arm, and thetwo layers 602, 603 are metallic in nature, although more generally thetwo layers 602, 603 may be comprised of any suitable materials havingsufficiently different thermal properties to carry out the functionsdescribed herein. The deformable member 601 is preferably anchored atone end 606 to a non-conductive surface 615. At its other end, thedeformable member 601 has a wedge-shaped member 651.

As further illustrated in FIG. 6, narrow end of the wedge-shaped member651 resides in close proximity to a pair of electrical contacts 652. Thepair of electrical contacts 652 reside in contact with a pair ofelectrical conductors 620, 625, the first electrical conductor 625serving as an incoming power wire and the second electrical conductor620 serving as a power delivery means to a load (not shown). In normaloperation, power from the first electrical conductor 625 is conductedthrough the electrical contacts 652 to the second electrical conductor620 and thereby to the load. The electrical contacts 652 are attached toa pair of non-conductive arms 657, which are anchored to a stablesurface 660. A pair of springs 655 or other such means applies force tothe non-conductive arms 657 and thereby maintains the electricalcontacts 652 in contact in normal operation.

The electrical path formed across the electrical contacts 652 may bebroken by application of a control signal to the deformable member 601.To this end, a heating element 645 (such as a resistive coil) is coupledto the deformable member 601 (e.g., wrapped around the deformable member601, where embodied as a resistive coil). The heating element 645 ispreferably controlled by a switch control circuit 640 connected theretoby a pair of signal lines 641, 642. When the switch control signaloutput from the switch control circuit 640 is not asserted, the heatingelement 645 is effectively disconnected (and thus inactive), and poweris delivered through the incoming power wire 625 across the electricalcontacts 652 to the electrical conductor 620, from which it can befurther distributed to the load. When, however, the switch controlsignal from the switch control circuit 640 is asserted, the heatingelement 645 heats up due to the effect of the current flowing throughthe heating element 645. Similar to the deformable member 301 previouslydescribed with respect to FIG. 3, the deformable member 601 ofcontrollable electronic switch 600 starts to bend. Eventually, as aresult of this bending, the wedge 651 if forced between the electricalcontacts 652, causing the contacts 652 to gradually separate (withsprings 655 gradually compressing), and breaking the electrical circuitpath between the incoming power signal line 625 and the electricalconductor 620, as illustrated in FIG. 7.

So long as the switch control signal from the switch control circuit 640is asserted, the heating element 645 continues to keep the deformablemember 601 bent and the electrical path between the incoming power wire625 and the electrical conductor 620 disconnected. Once the switchcontrol signal from the switch control circuit 640 is de-asserted, thedeformable member 601 gradually cools, until eventually the deformablemember 601 is no longer deformed. As this occurs, the wedge 651gradually retracts, causing the electrical contacts 652 to come togetherand once again form an electrical connection, which in turn allows thepower signal to pass from the incoming power wire 625 to the electricalconductor 620 and then to the load.

In one aspect, the controllable electronic switch 600 illustrated inFIG. 6, like the controllable electronic switch 300 of FIG. 3, canprovide a convenient, inexpensive mechanism for controlling thedistribution of power from a source to a load. Moreover, thecontrollable electronic switch 600 need not consume any power when theelectrical contacts 652 are in a closed position, and only requiresminimal power to cause the deformable member 601 to bend and theelectrical contacts 652 to spread apart, opening the power signalcircuit path.

FIG. 8 is a diagram of another embodiment of a controllable electronicswitch 800 using a wedge-shaped member to break electrical contacts in acircuit path. Many of the components shown in FIG. 8 are similar innature to those illustrated in FIG. 6. Thus, for example, thecontrollable electronic switch 800 of FIG. 8 comprises a generallyelongate deformable member 801 which is formed of two layers 802, 803,similar in nature to the deformable member(s) 301, 601 describedpreviously with respect to FIGS. 3 and 6, respectively. In a preferredembodiment, the deformable member 801 comprises a bimetal arm, and thetwo layers 802, 803 are metallic in nature, although more generally thetwo layers 802, 803 may be comprised of any suitable materials havingsufficiently different thermal properties to carry out the functionsdescribed herein. The deformable member 801 is preferably anchored atone end 806 to a non-conductive surface 815. At its other end, thedeformable member 801 has a wedge-shaped member 851 that, as will bedescribed in more detail below, functions as a mechanical cam.

As further illustrated in FIG. 8, one end of the wedge-shaped member 851resides in close proximity to a pair of electrical contacts 852. Thepair of electrical contacts 852 reside in contact with a pair ofelectrical conductors 820, 825, the first electrical conductor 825serving as an incoming power wire and the second electrical conductor820 serving as a power delivery means to a load (not shown). In normaloperation, power from the first electrical conductor 825 is conductedthrough the electrical contacts 852 to the second electrical conductor820 and thereby to the load. The electrical contacts 852 are attached toa pair of non-conductive arms 857, which are anchored to a stablesurface 860. A pair of springs 855 or other such means applies force tothe non-conductive arms 857 and thereby maintains the electricalcontacts 852 in contact in normal operation.

Similar to the FIG. 6 embodiment, the electrical path formed across theelectrical contacts 852 may be broken by application of a control signalto the deformable member 801. To this end, a heating element 845 (suchas a resistive coil) is coupled to the deformable member 801 (e.g.,wrapped around the deformable member 801, where embodied as a resistivecoil). The heating element 845 is preferably controlled by a switchcontrol circuit 840 connected thereto by a pair of signal lines 841,842. When the switch control signal output from the switch controlcircuit 840 is not asserted, the heating element 845 is effectivelydisconnected (and thus inactive), and power is delivered through theincoming power wire 825 across the electrical contacts 852 to theelectrical conductor 820, from which it can be further distributed tothe load. When, however, the switch control signal from the switchcontrol circuit 840 is asserted, the heating element 845 heats up due tothe effect of the current flowing through the heating element 845, andas a result the deformable member 801 starts to bend. Eventually, as aresult of this bending, the wedge 851 if forced between the electricalcontacts 852, causing the contacts 852 to gradually separate (withsprings 855 gradually compressing), and breaking the electrical circuitpath between the incoming power signal line 825 and the electricalconductor 820, similar to the illustration in FIG. 7.

Unlike the embodiment of FIG. 6, the wedge-shaped member 851 of thecontrollable electronic switch 800 of FIG. 8 acts as a mechanical camwith multiple latching positions, thus alleviating the need to maintainthe control signal to keep the circuit open. When the wedge-shapedmember 851 is latched in a first position, it is removed from theelectrical contacts 852, which remain closed, and the power signalcircuit path is uninterrupted. On the other hand, when the wedge-shapedmember 851 is latched in a second position, it forces the electricalcontacts 852 apart, thus interrupting the power signal circuit path. Ineither latched position, no power is required to keep the controllableelectronic switch 800 in its current state (open or closed). Latching ofthe wedge-shaped member 851 in the various positions is accomplished, inthis example, by way of a latching member 880 comprising, e.g., an arm882 terminated in a ball 881 that rests against the wedge-shaped member851. In the instant example, the arm 882 of the latching member 880 isanchored to surface 860, but the latching member 880 may be anchored toany other available surface instead. Thus, in this example, the latchingmember 880 is adjacent to the arms 857 supporting the electricalcontacts 852.

FIGS. 9-1, 9-2 and 9-3 are diagrams of different views illustrating anexample of the wedge-shaped member 851 of the controllable electronicswitch 800 of FIG. 8, and in particular FIGS. 9-2 and 9-3 illustrate thewedge-shaped member 851 of FIG. 9-1 latched in the first position. Thewedge-shaped member 851 in this example comprises a front wedge section905 (which may be generally broad-surfaced and sloping), a centralsocket 901, and a rear wedge section 906 (which may be tapered andsloping) defining a shallow rear socket 908. As best illustrated inFIGS. 9-2 and 9-3, the ball 881 of the latching member 880 rests on thefront wedge section 905 when the wedge-shaped member 851 is latched inthe first position (the arm 882 is omitted from FIGS. 9-2 and 9-3 forclarifying the other features shown). The ball 881 may effectively holdthe wedge-shaped member 851 in place when latched in the first position,although in certain embodiments the ball 881 may not need to contact thewedge-shaped member 851 and would generally lie in proximity therewith.

FIGS. 10-1 through 10-8 are diagrams illustrating how the wedge-shapedmember 851 transitions between different latching positions. FIGS. 10-1and 10-2 are similar to FIGS. 9-2 and 9-3, respectively, and show thewedge-shaped member 851 at rest in the first latched position. FIG. 10-3illustrates what happens as the deformable member 801 is heated inresponse to the control signal being applied to the heating element 845(shown in FIG. 8). In this situation, the deformable member 801 startsto bend, forcing the wedge-shaped member 851 forward. When that occurs,the ball 881 slides over the sloping surface of the front wedge section905, and comes to rest in the central socket 901 of the wedge-shapedmember 851, causing the wedge-shaped member to stabilize in the secondlatched position. For comparative purposes, the first latched positionis represented by a dotted outline 851′ of the wedge-shaped member,although the actual dimensions of movement may be somewhat exaggeratedfor illustration purposes. In practice, movement of the wedge-shapedmember 851 by only a few hundredths of an inch may be sufficient tochange latched positions. Even after the control signal is de-asserted,the ball 881 retains the wedge-shaped member 851 in the second latchedposition, by virtue of its resting firmly in the central socket 901. Thewedge-shaped member 851 thereby keeps the contacts 852 separated whileit is held in the second latching position.

Application of a subsequent control signal causes the wedge-shapedmember 851 to return to the first latched position. When the subsequentcontrol signal is applied, the deformable member 801 again heats up,causing it to bend and the wedge-shaped member 851 to gravitateforwards. The ball 881 is thereby forced out of the central socket 901and onto the second wedge section 906, as illustrated in FIG. 10-5. Theball 881 slides down the tapered surface of the second wedge section906, and due to the very narrow tail end of the second wedge section 906(which is preferably asymmetrically tapered) the ball 881 slides off themore sharply tapered side of the second sedge section 906 and iscaptured by the upper lip of the shallow rear socket 908, as illustratedin FIG. 10-6. The upper lip of the shallow rear socket 908 helps guidethe ball 881 along the outer side surface 910 of the wedge-shaped member851, as illustrated from a side view in FIG. 10-7 and a top view in FIG.10-8, during which time the arm 882 of the latching member 880 may beforced slightly to the side of the wedge-shaped member 851 (or viceversa). As the deformable member 801 cools, the ball 881 slides alongthe outer side surface 910 of the wedge-shaped member 851 and eventuallyreaches the narrow tip region of the front wedge section 905, whereuponthe arm 882 of the latching member 880 straightens out and forces theball 881 onto the surface of the front wedge section 905, returning thewedge-shaped member 851 to the first latched position as illustrated inFIGS. 10-1 and 10-2.

The above process may be repeated as desired to allow the controllableelectronic switch 880 to open and close the electrical contacts 852 byhaving the wedge-shaped member 851 move between the first and secondlatched positions. The control signal that is applied to cause thewedge-shaped member 851 to move may take the form of, e.g., an impulsesignal.

FIG. 11 is a diagram of yet another embodiment of a controllableelectronic switch 1100 using a wedge-shaped member to break electricalcontacts in a circuit path, again employing principles of a mechanicalcam with multiple latching positions. In FIG. 11, the controllableelectronic switch 1100 comprises a generally elongate deformable member1101 which, as before, is formed of two layers 1102, 1103, similar innature to, e.g., the deformable member(s) 301, 601 described previouslywith respect to FIGS. 3 and 6, respectively. In a preferred embodiment,the deformable member 1101 comprises a bimetal arm, and the two layers1102, 1103 are metallic in nature, although more generally the twolayers 1102, 1103 may be comprised of any suitable materials havingsufficiently different thermal properties to carry out the functionsdescribed herein. The deformable member 1101 is preferably anchored atone end to a non-conductive surface 1160. At its other end, thedeformable member 1101 has a wedge-shaped member 1151 that, as will bedescribed in more detail below, functions as a mechanical cam.

As further illustrated in FIG. 11, a pivoting arm 1180 is positionedbetween the first wedge-shaped member 1151 and a pair of electricalcontacts 1152. The pair of electrical contacts 1152 reside in contactwith a pair of electrical conductors 1120, 1125, the first electricalconductor 1125 serving as an incoming power wire and the secondelectrical conductor 1120 serving as a power delivery means to a load(not shown). In normal operation, power from the first electricalconductor 1125 is conducted through the electrical contacts 1152 to thesecond electrical conductor 1120 and thereby to the load. The electricalcontacts 1152 are attached to a pair of non-conductive arms 1157, whichare anchored to a stable surface (not shown). A pair of springs (notshown, but similar to springs 855 in FIG. 8) or other such means appliesforce to the non-conductive arms 1157 and thereby maintains theelectrical contacts 1152 in contact in normal operation.

As further illustrated in FIG. 11, the pivoting arm 1180 has a ball 1181at one end and a second wedge-shaped member 1161 at the opposite end.The pivoting arm 1180 may be secured to a fixed structure 1185 at, e.g.,a generally centrally located pivoting point 1184.

The electrical path formed across the electrical contacts 1152 may bebroken by application of a control signal to the deformable member 1101.To this end, a heating element 1145 (such as a resistive coil) iscoupled to the deformable member 1101. The heating element 1145 ispreferably controlled by a switch control circuit 1140 connected theretoby a pair of signal lines 1141, 1142. When the switch control signaloutput from the switch control circuit 1140 is not asserted, the heatingelement 1145 is effectively disconnected (and thus inactive), and poweris delivered through the incoming power wire 1125 across the electricalcontacts 1152 to the electrical conductor 1120, from which it can befurther distributed to the load. When, however, the switch controlsignal from the switch control circuit 1140 is asserted, the heatingelement 1145 heats up due to the effect of the current flowing throughthe heating element 1145, and as a result the deformable member 1101starts to bend. Eventually, as a result of this bending, thewedge-shaped member 1151 presses the ball 1181 of pivoting arm 1180 suchthat it becomes displaced as the pivoting arm 880 is forced to rotateslightly in the clockwise direction. This motion forces the other end ofthe pivoting arm 1180 to move in a clockwise direction, which in turnforces the second wedge-shaped member 1161 between the electricalcontacts 1152. This action causes the contacts 1152 to graduallyseparate, and breaks the electrical circuit path between the incomingpower signal line 1125 and the electrical conductor 1120, as illustratedin FIG. 12.

Similar the embodiment of FIG. 8, the wedge-shaped member 1151 of thecontrollable electronic switch 1100 of FIG. 11 acts as a mechanical camwith multiple latching positions, thus alleviating the need to maintainthe control signal to keep the circuit open. When the first wedge-shapedmember 1151 is latched in a first position, it causes the secondwedge-shaped member 1161 to be removed from the electrical contacts1152, which remain closed, and the power signal circuit path isuninterrupted. On the other hand, when the first wedge-shaped member1151 is latched in a second position, it causes the second wedge-shapedmember 1161 to force the electrical contacts 1152 apart, thusinterrupting the power signal circuit path. In either latched position,no power is required to keep the controllable electronic switch 1100 inits current state (open or closed). Latching of the wedge-shaped member1151 in the various positions is accomplished, in this example, by thepivoting arm 1180 which, similar to latching member 880, is terminatedin a ball 1181 that rests against the wedge-shaped member 1151.

Motion of the ball 1181 with respect to the first wedge-shaped member1151 is similar to the described with respect to the controllableelectronic switch 800 of FIG. 8 and the illustrations in FIGS. 9-1through 9-3 and 10-1 through 10-8. However, rather than the firstwedge-shaped member 1151 itself being inserted between the contracts1152 to open them, the first wedge-shaped member 1151 causes thepivoting arm 1180 to swing back and forth, thereby causing the secondwedge-shaped member 1161 to move forwards and backwards and to open andclose the electrical contacts 1152.

It should be noted that the embodiments illustrated in FIGS. 8 and 11,and elsewhere, are merely examples and are not intended to be exhaustivenor limiting of the concepts and principles disclosed herein. Whilecertain cam mechanisms have been described and illustrated, and cam orother similar mechanism may also be used to perform similar functions.Alternative embodiments may include, for example, any member that isused in connection with separating electrical contacts (or other type ofcircuit connection), has at least one stable position and one or moreunstable positions, and transitions between the stable and unstablepositions through application of a control signal. A variety ofdifferent mechanical structures can be utilized in place of thewedge-shaped member(s) described herein and illustrated in the drawings

FIGS. 18, 20 and 22 are diagrams illustrating additional controllableswitch embodiments. FIG. 18 is a diagram of another embodiment of acontrollable electronic switch similar to the controllable switch shownin FIG. 3, but with a different location of the incoming power wireillustrated. As shown in FIG. 18, a controllable electronic switch 1800comprises a deformable member 1801, similar to FIG. 3, which may beformed in the general shape of an arm and may be comprised of two layers1802, 1803 having different thermal properties. The deformable member1801 is preferably anchored at one end 1806 to a non-conductive surface1815. At its other end, the deformable member 1801 preferably resides incontact with an electrical conductor 1820 through contacts 1807, 1812.An incoming power wire 1825 is connected to the deformable member 1801preferably near anchor point 1806. As with FIG. 3, the electricalconductor 1820 may be connected to a load (not shown) and, in normaloperation (that is, in the absence of assertion of a switch controlsignal, as explained below), power from the power signal line 1825 isconducted through the deformable member 1801 and the electricalconductor 1820 to the load.

The conductive substances of the different layers 1802, 1803 of thedeformable member 1801 are preferably selected to have different thermalproperties such that they heat at different rates. A heating element1845 (such as a resistive coil) is coupled (e.g., wrapped around, in thecase of a resistive coil) to the deformable member 1801. The heatingelement 1845 is preferably controlled by a switch control circuit 1840in a similar manner to the controllable switch 300 of FIG. 3. When theswitch control signal output from the switch control circuit 1840 is notasserted, the heating element 1845 is effectively disconnected (and thusinactive), and power is delivered through the incoming power wire 1825over the deformable member 1801 to the electrical conductor 1820, fromwhich it can be further distributed to the load. This operation isillustrated in FIG. 19-1. On the other hand, when the switch controlsignal from the switch control circuit 1840 is asserted, the heatingelement 1845 heats up, causing the deformable member 1801 to bend andbreak the electrical circuit path between the incoming power signal line1825 and the electrical conductor 1820, as illustrated in FIG. 19-2.

So long as the switch control signal from the switch control circuit1840 is asserted, the heating element 1845 continues to keep thedeformable member 1801 bent and the electrical path between the incomingpower wire 1825 and the electrical conductor 1820 disconnected. Once theswitch control signal from the switch control circuit 1840 isde-asserted, the deformable member 1801 gradually cools, untileventually the deformable member 1801 is no longer deformed. As thisoccurs, the contacts 1807, 1812 once again form an electricalconnection, allowing the power signal to pass from the incoming powerwire 1825 to the electrical conductor 1820 and then to the load.

When too much current is being drawn by the load such that anover-current situation exists, then the deformable member 1801 also willbend, breaking the electrical connectivity between the incoming powerwire 1825 and the electrical conductor 1820 (hence disconnecting powerfrom the load). Thus, the controllable electronic switch 1800illustrated in FIG. 18 may act as both a circuit breaker, responsive toover-current, and a controllable electronic switch, responsive to acontrol signal.

FIG. 20 is a diagram of a controllable electronic switch 2001, utilizinga pair of opposing deformable members (e.g., bimetal arms). As shown inFIG. 20, the controllable electronic switch 2001 includes a firstdeformable member 2051 and a second deformable member 2052, each ofwhich may be formed in the general shape of an arm, facing one another,and may, as previously described, be comprised of two layers havingdifferent thermal properties. The opposing deformable members 2051, 2052are preferably anchored to a non-conductive surface 2060. At their otherends, the deformable members 2051, 2052, when at rest, preferably residein contact with one another through contacts 2012 and 2013,respectively, and may also are separated from one another by a restingbar 2009. One of the deformable members 2052 is electrically coupled toan incoming power wire 2025, preferably near the anchor point on thenon-conductive surface 2025. The other deformable member 2051 ispreferably electrically coupled to an electrical wire (or otherconductor) 2020 which may in turn be connected to a load (not shown). Innormal operation (that is, in the absence of assertion of a switchcontrol signal, as explained below), power from the incoming power line2025 is conducted through the deformable member 2052 and the electricalwire 2020 to the load.

The conductive substances of the different layers of the deformablemembers 2051, 2052 are preferably selected to have different thermalproperties such that they heat at different rates. When too much currentis being drawn by the load such that an over-current situation exists,then the deformable member 1852 will bend and break the connectionbetween the electrical contacts 2012, 2013, as illustrated in FIG. 21-1,thereby breaking the supply of power from the incoming power wire 2025and the electrical wire 2020 (i.e., the load). The resting bar 2009prevents the non-circuit-breaker deformable member 2051 from followingthe bending deformable member 2052, which would otherwise hinder orprevent the bending deformable member 2052 from breaking the circuitconnection.

A heating element 2045 (in this example, resistive tape, but could alsobe a resistive coil or other means) is placed proximate to (e.g., as anadherent, in the case of a resistive tape) to one of the deformablemembers 2051. The heating element 2045 is preferably controlled by aswitch control circuit 2040 in a similar manner to the controllableswitch 300 of FIG. 3. When the switch control signal output from theswitch control circuit 2040 is not asserted, the heating element 2045 iseffectively disconnected (and thus inactive), and power is deliveredthrough the incoming power wire 2025 over the deformable member 2052 andcontacts 2012, 2013 to the electrical wire 2020, from which it can befurther distributed to the load. This operation is conceptuallyillustrated in FIG. 18. On the other hand, when the switch controlsignal from the switch control circuit 2040 is asserted, the heatingelement 2045 heats up, causing the deformable member 2051 to bend andbreak the electrical circuit path between the incoming power signal line2025 and the electrical wire 2020, as illustrated in FIG. 21-2. Asbefore, the resting bar 2009 prevents the non-bending deformable member2052 from following the bending deformable member 2051, which wouldotherwise hinder or prevent the bending deformable member 2051 frombreaking the circuit connection.

So long as the switch control signal from the switch control circuit2040 is asserted, the heating element 2045 continues to keep thedeformable member 2051 bent and the electrical path between the incomingpower wire 2025 and the electrical wire 2020 decoupled. Once the switchcontrol signal from the switch control circuit 2040 is de-asserted, thedeformable member 2051 gradually cools, until eventually the deformablemember 2051 is no longer deformed. As this occurs, the contacts 2012,2013 once again form an electrical connection, allowing the power signalto pass from the incoming power wire 2025 to the electrical wire 2020and then to the load.

In one aspect, the controllable electronic switch 2001 illustrated inFIG. 20 may act as both a circuit breaker, responsive to over-current,and a controllable electronic switch, responsive to a control signal.The first deformable member 2052 acts in one respect as a “safety arm,”bending in response to over-current, while the other deformable member2051 acts in one respect as a “control arm,” bending in response to acontrol signal from switch control circuit 2040.

FIG. 22 is a diagram of another embodiment of a controllable electronicswitch having opposing deformable members and a override control. Thecontrollable electronic switch 2201 in FIG. 22 is similar to that shownin FIG. 20, with elements numbered “22xx” in FIG. 22 similar to theircounterparts numbers “20xx” in FIG. 20, except that a rotatable cam 2219is used in FIG. 22 in place of a resting bar 2009 shown in FIG. 20. Thegeneral operation of the controllable electronic switch 2201 in FIG. 22is the same a that of FIG. 20. However, the rotatable cam 2219 providesa mechanism for overriding the operation of either of the deformablemembers 2251, 2252. The operation of the rotatable cam 2219 isillustrated in FIGS. 23-1 and 23-2. In FIG. 23-1 is illustrated anover-current condition that has caused deformable member 2252 to bend,breaking the circuit connection with the load. This is similar to thesituation illustrated previously in FIG. 21-1. However, rotation of therotatable cam 2219 allows the other deformable member 2251 to movetowards the opposing deformable member 2252, using the naturalspring-like tension of the deformable member 2251, until the contacts2212, 2213 eventually touch and re-connect the circuit.

A control circuit (not shown) controls the rotation of rotatable cam2219, and may be electrical or mechanical in nature. For example, thecontrol circuit may be responsive to a remote signal, or else to amanually activated electrical or mechanical switch. The amount ofrotation needed for rotatable cam 2219 to allow the deformable members2251, 2252 to contact each other may be preset. Alternatively, or inaddition, a sensing circuit along the path of electrical flow can beused to detect whether current is flowing across contacts 2212, 2213,and the control circuit can continue to rotate the rotatable cam 2219(to a limit point, if desired) until resumption of power flow isdetected by the sensing circuit.

In the exemplary embodiment shown in FIG. 22, the rotatable cam 2219provides override capability in either direction. Thus, when deformablemember 2251 is caused to bend by application of a control signal fromswitch control circuit 2240, thus stopping the flow of power to theload, the control signal may effectively be overridden by rotation ofthe rotatable cam 2219 in the opposite direction than that shown in FIG.23-2. This causes deformable member 2252 to move towards the opposingdeformable member 2251, using the natural spring-like tension of thedeformable member 2252, until the contacts 2212, 2213 eventually touchand re-connect the circuit. In other words, the override feature worksin the same way as illustrated for FIG. 23-2, but in the oppositedirection. When rotatable cam 2219 is stationary in its “normal”operating position, as illustrated in FIG. 22, it acts as a resting arm(similar to 2009 in FIG. 20), preventing the deformable members 2251,2252 from following one another when either is activated under theconditions causing them to bend and break the flow of power to the load.

An override capability such as provided by rotatable cam 2219 may beuseful in a variety of applications. For example, it may be desirable tooverride the operation of deformable member 2251 or 2252 in case of amalfunction. If the controllable electronic switch 2001 or 2201 isdeployed as part of a system for a remote control of power distributionto local loads, then it may be desirable to allow a local user tooverride a command from a remote source which has instructed deformablemember 2251 to cut off power to its load—for example, in case there isan emergency requiring the local load to receive power. Likewise, ifdeformable member 2252 has “tripped” causing a cut-off of power flow tothe local load, then an override capability may be desirableparticularly in an emergency situation where it is expected that theload can absorb the extra current. As an example, if the load is alanding gear of an airplane which has stuck, causing an overcurrentsituation and thus deformable member 2252 to trip, it may be desirableto allow a manual override capability whereby power to the landing gearcan be re-connected, especially if it is expected that the additionalpower will not harm the landing gear and/or may cause it to unjam. It isexpected that many other such situations could be envisioned by thoseskilled in the art.

While the rotatable cam 2219 is illustrated in FIG. 22 as generallysemi-circular in shape, the shape of the cam can be of any (e.g., oval)that is suitable to cause deformable members 2251, 2252 to move closerto one another when the rotatable cam 2219 is rotated. Alternatively,other types of mechanisms may be used. For example, resting bar 2009 inFIG. 20 may be slidable towards each of the deformable members 2051,2052, and can be moved towards the bending deformable member 2051 (or2052) to allow the electrical contacts 2012, 2013 to re-connect, thusproviding a similar override feature. Similarly, a tapered or conicalresting bar 2009 may be used, which can be raised and lowered, therebyincreasing and decreasing the distance between the deformable members2051, 2052 as desired. Alternatively, a bypass conductive bridge (notshown) may be moved from a normally non-contacting position to a contactposition across deformable members 2051, 2052, thus providing aneffective override by establishing an alternative path for current toflow across deformable members 2051, 2052. In short, any means may beused which results in deformable members 2051, 2052 (or 2251, 2252)rejoining their connection to allow power to flow through to the load.

In one aspect, as with the controllable electronic switch of FIG. 20,the controllable electronic switch 2201 illustrated in FIG. 22 may actas both a circuit breaker, responsive to over-current, and acontrollable electronic switch, responsive to a control signal. Thefirst deformable member 2252 acts in one respect as a “safety arm,”bending in response to over-current, while the other deformable member2251 acts in one respect as a “control arm,” bending in response to acontrol signal from switch control circuit 2240. Preferably, an overridefeature is provided whereby the operation of the control arm or safetyarm in breaking the circuit can be overridden. In the particular exampleof FIG. 22, in one aspect, a t 3-position rotating cam 2219 providesoverride control, with one position being used for “normal” operatingmode, a second position for override of bending of the “safety arm,” anda third position for override of bending of the “control arm.”

In the various embodiments disclosed herein, any appropriate means forheating the deformable member (e.g., bimetal arm) may be utilized,including not only a resistive coil, resistive tape, or a small thermalresisistor, but also other means as well.

FIGS. 13, 14, and 15 are simplified schematic diagrams of examples ofcontrol circuits or portions thereof that may be used with variouscontrollable electronic switches disclosed herein. In FIG. 13, a controlsignal generator 1300 includes a power source 1370 (e.g., battery orother DC source) connected via a first switch 1371 to a capacitor 1374.The capacitor 1374 is connected via a second switch 1372 to a heatingelement 1345, such as a resistive coil, which is proximate to adeformable member 1301. The heating element 1345 and deformable member1301 may represent similar components which are illustrated in FIG. 8 or11 or any of the other controllable electronic switch embodimentsdescribed herein.

In operation, the power source 1370 maintains capacitor 1374 in acharged state when switch 1371 is closed and switch 1372 is open. Sinceswitch 1372 is open, the heating element 1345 is disengaged, and thedeformable member 1301 remains in its natural unheated state. To apply acontrol signal to the heating element 1345, a control circuit (notshown) opens switch 1371 and closes 1372, as illustrated in FIG. 14. Asa result, power source 1370 is disengaged from capacitor 1374, and thecapacitor 1374 discharges into the heating element 1345. The capacitor1374 may be selected to be of sufficient size and rating to hold theappropriate amount of charge to cause heating element 1345 to heat upsufficiently to cause the deformable member 1301, particularly ifembodied as a latching cam mechanism (such as in FIGS. 8 and 11, forexample), to be forced into the next latched state. Once the capacitor1374 has been substantially discharged, switch 1371 may be closed andswitch 1372 opened, to recharge the capacitor 1374. The switches 1371,1372 may then again be toggled to discharge the capacitor 1374 a secondtime and cause the deformable member 1301, where embodied as a latchingcam mechanism, to be forced into another latched state (or returned toits original latched state).

FIG. 15 applies the same principles of FIGS. 13 and 14 to a system ofcontrollable electronic switches. The control circuit system 1500 ofFIG. 15 includes a power source 1570 and capacitor 1574 similar to thecounterparts of FIGS. 13 and 14. A first switch 1571 is analogous toswitch 1371 in FIGS. 13 and 14, and is generally closed when chargingthe capacitor 1574. When it is desired to activate the controllableelectronic switches, a control circuit 1576 opens switch 1571 and closesthe switches 1572 a, 1572 b, 1572 c, . . . associated with thecontrollable electronic switches to be activated. Only selected ones ofthe switches 1572 a, 1572 b, 1572 c, . . . need be activated, accordingto the programming of the control circuit 1576. For the switches 1572 a,1572 b, 1572 c, . . . that are closed, the respective heating elements(e.g., resistive coils) 1545 a, 1545 b, 1545 c, . . . heat up, causingdeformation of the proximate deformable members and activation of thecontrollable electronic switches according to principles previouslydescribed herein.

FIG. 16 is a diagram of an embodiment of a switch control circuit 1601as may be used in connection with various controllable electronic switchembodiments shown or described herein—for example, the controllableelectronic circuits shown in FIG. 3, 5, or 6, or others. As illustratedin FIG. 16, the switch control circuit 1601 comprises an incoming ACpower signal 1605 which is coupled to a capacitor 1608, which in turn isconnected to a heating element (not shown) via an electronic orelectro-mechanical switch 1623. A manual toggle switch or button 1620 isused to activate the electronic or electro-mechanical switch 1623, whichselectively allows the incoming power signal 1605 to pass to the heatingelement 1625. The incoming AC power signal 1605 may be, e.g.,single-phase electrical power drawn from a power line, and the designillustrated in FIG. 16 thereby provides a low cost, high efficiencymechanism (with minimal current drain) for activating the controllableelectronic switch.

FIG. 17 is a diagram of another embodiment of a switch control circuit1701 as may be used in connection with various controllable electronicswitch embodiments as shown or described herein—for example, thecontrollable electronic circuits shown in FIG. 3, 5, or 6, or others. Asillustrated in FIG. 17, the switch control circuit 1701 comprises anincoming AC power signal 1705 which is coupled to a capacitor 1708,which in turn is connected to a heating element (not shown) via anelectronic 1723. A receiver 1720 receives a remote command signal viaantenna 1718 and, in response thereto, opens or closes the switch 1723,which selectively allows the incoming power signal 1605 to pass to theheating element 1725. The receiver 1720 may be configured to communicateusing any wireless technique, and may, for example, be advantageouslyconfigured to receive signals transmitted using either frequency shiftkeying (FSK) or FM sideband transmission. More complicated commands maybe delivered via the receiver 1720, thereby allowing the switch controlcircuit 1701 to be utilized as part of a circuit control system thatcontrols the states numerous controllable electronic switches and allowsmore complex processes and decisions to be carried out. The incoming ACpower signal 1705 may be, e.g., single-phase electrical power drawn froma power line, and the design illustrated in FIG. 17 thereby provides arelatively low cost, flexible, and high efficiency mechanism (withminimal current drain) for activating the controllable electronicswitch.

Various embodiments as disclosed herein provide a simple, effective,reliable and inexpensive controllable electronic switch capable ofcontrolling the distribution of power signals (either low voltage and/orcurrent or high voltage and/or current) from a power signal source to aload. Moreover, the controllable electronic switch need not consume anypower when the switch is closed, and takes only minimal or no power toopen and maintain open. Certain embodiments can allow remote operationof the controllable electronic switch, thus providing a flexible andconvenient mechanism to control power distribution. The variousembodiments as disclosed herein may be utilized in connection with powercontrol systems and circuits disclosed, for example, in copending U.S.patent application Ser. No. 10/007,501 and/or Ser. No. 10/006,463, bothof which were filed Nov. 30, 2001, are assigned to the assignee of thepresent invention, and are hereby incorporated by reference as if setforth fully herein.

While preferred embodiments of the invention have been described herein,many variations are possible which remain within the concept and scopeof the invention. Such variations would become clear to one of ordinaryskill in the art after inspection of the specification and the drawings.The invention therefore is not to be restricted except within the spiritand scope of any appended claims.

What is claimed is:
 1. A method for controlling an electronic switch andthereby connecting and disconnecting an incoming power signal from aload, comprising: providing a pair of electrical contacts; positioning apair of opposing elongate heat-deformable members on opposing sides of aresting member disposed therebetween, said elongate heat-deformablemembers each associated with one of the pair of electrical contacts andoriented such that the electrical contacts are electrically coupled whenthe elongate heat-deformable members are at rest, wherein the restingmember comprises a semi-circular rotatable cam having a first end and asecond end, wherein when the rotatable cam is in a first unrotatedposition the opposing elongate heat-deformable members are separated ifeither of them is deformed such that an electrical connection is brokenbetween the pair of electrical contacts, and wherein when the rotatablecam is in a second rotated position the non-deformed elongateheat-deformable member is permitted to bend towards the deformedelongate heat-deformable member and re-establish the electricalconnection between the pair of electrical contacts; and controllablyseparating the pair of electrical contacts by allowing either of theelongate heat-deformable members to bend while inhibiting the opposingelongate heat-deformable member from following the bending elongateheat-deformable member by virtue of the resting member, and theinhibited elongate heat-deformable member remaining stationary while theother heat-deformable member bends and thereby connecting anddisconnecting the incoming power signal from the load.
 2. The method ofclaim 1, wherein the elongate heat-deformable members each have a fixedend and a free end, and wherein said pair of electrical contacts arerespectively disposed at the free ends of said pair of elongateheat-deformable members.
 3. The method of claim 2, further comprising:coupling an incoming power signal line terminating to a fixed end of afirst one of said pair of elongate heat-deformable members; and couplingan output power signal line proximate to the electrical contact disposedon a second one of said pair of elongate heat-deformable members, suchthat power from said incoming power signal line flows through said firstelongate heat-deformable member, across said pair of electricalcontacts, and through the output power signal line to the load but doesnot flow through said second elongate deformable member.
 4. The methodof claim 1, wherein one of said elongate heat-deformable members acts asa safety arm which breaks circuit connection upon an over-currentcondition while the other arm remains stationary, and wherein the otherone of said elongate heat-deformable members acts as a control armbreaking circuit connection in response to an electronic control signalwhile the other arm remains stationary.
 5. The method of claim 4,further comprising heating the elongate heat-deformable member acting asa control arm in order to cause it to break circuit connection inresponse to said control signal.
 6. The method of claim 5, wherein saidheating is carried out by applying a current through resistive tapedisposed upon said elongate heat-deformable member acting as a controlarm but not to the heat-deformable elongate member acting as a safetyarm.
 7. The method of claim 5, wherein said heating is carried out usinga heating coil disposed proximate to said elongate heat-deformablemember acting as a control arm but not to the heat-deformable elongatemember acting as a safety arm.
 8. The method of claim 5, wherein saidresting member moves and thereby overrides the operation of eitherelongate heat-deformable member by controllably allowing the elongateheat-deformable members to reconnect.
 9. The method of claim 1, furthercomprising rotating said rotatable cam from a normal operating positionto an override position in order to cause said opposing elongateheat-deformable members to move towards one another and reconnect powerto the load.
 10. The method of claim 9, wherein rotation of saidrotatable cam is responsive to a manual switch.
 11. The method of claim1, wherein said elongate heat-deformable members each comprise a bimetalarm.
 12. The method of claim 11, wherein each of said bimetal arms has atop side comprised of a first metallic substance and a bottom sidecomprised of a second metallic substance having different thermalproperties than the first metallic substance.
 13. The method of claim 1,further comprising conveying power from the incoming power signal to theload through an electrical conductor when said pair of electricalcontacts are in contact with one another, and avoiding the conveyance ofpower to the load when said pair of electrical contacts are separatedfrom one another.
 14. A method of selectively providing power to a load,comprising: positioning a pair of elongate bimetallic members in anopposing relationship, said elongate bimetallic members coupled to apair of separable electrical contacts which can be moved to connect anddisconnect an incoming power signal to or from a load; disposing aresting member between said elongate bimetallic members such that wheneither elongate bimetallic member bends in response to being heated, theopposing elongate bimetallic member is inhibited from following thebending elongate bimetallic member and thereby remains stationary,wherein the resting member comprises a semi-circular rotatable camhaving a first end and a second end, wherein when the rotatable cam isin a first unrotated position the opposing elongate heat-deformablemembers are separated if either of them is deformed such that anelectrical connection is broken between the pair of electrical contacts,and wherein when the rotatable cam is in a second rotated position thenon-deformed elongate heat-deformable member is permitted to bendtowards the deformed elongate heat-deformable member and re-establishthe electrical connection between the pair of electrical contacts;controllably separating the pair of electrical contacts in anover-current condition that causes the first one of said pair ofelongate bimetallic members to bend away from the second elongatebimetallic member but which does not affect the second elongatebimetallic member; and controllably separating the pair of electricalcontacts by heating the second one of said pair of elongate bimetallicmembers, causing it to bend away from the first elongate bimetallicmember which remains stationary.